K. Jensch - DESY Requirements Conformance for SRF Cryomodules Workshop 16/10/2014 – ESS, Lund XFEL cryomodules: Quality Requirements and Regulatory & Safety issues

2 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Summary Regulatory requirements for the XFEL project  PED and the XFEL cold linac  From one linac to the single cryomodule  Different roles: manufacturer and external authority  An example: the 3.9 GHz cryomodule Quality requirements versus Regulatory requirements  An example: the 2-phase pipe repair work of the XFEL cavities Conclusions

3 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch PART 1 Regulatory requirements for the XFEL project

4 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Regulations applicable to the XFEL cold linac For operation, the XFEL linac has to fulfill the requirements of the „Betriebsicherheitsverordung“ (German implementation of the Directive 2009/104/EC, use of work equipment) In Hamburg this means that the linac needs for operation the approval from the „Amt für Arbeitsschutz (AfA, HH)“ (office for work safety) The AfA does not verify the facility itself -> certification (e.g. CE) of the linac via a notified body (TÜV Nord) The CE marking of single components is the manufacturer's declaration that the product meets the requirements of the applicable EC directives; for Pressure Vessels -> PED

5 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch What’s PED about? PED applies only to the production of single components (for operation  Norm 2009/104/EC) The PED „provides for a flexible regulatory environment that does not impose any detailed technical solution”, i.e. it‘s not a „manual how to build“, but includes the minimal requirements that you have to fulfill For example, it doesn‘t define which materials are allowed, but it requires (see PED Annex I.4.2b) that materials used for pressure equipment must fulfill one of the following three formal requirements:  comply with a Harmonized Standard Material;  be covered by a European Approval of Material (EAM);  particular material appraisal (PMA).

6 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch CE certification of an XFEL cryomodule The XFEL cryomodule is an assembly (Baugruppe), made of the following „PED relevant“ sub-components:  8 cavities  1 quadrupole  7 titanium bellows cavity string  1 end connection  1 quadupole pipe  1 cold mass, also an assembly of all the cooling pipes Each of this components is independently certified as a „part of a pressure equipment“ (Druckgeräteteilen) by the TÜV or by DESY (as an approved manufactor according to AD2000 HP0 and EN3834) Only the entire cryomodule is certified as a „pressure equipment“ (Druckgeräte) -> currently is under discussion if each module get a CE stamp or one CE for the cold linac as a „group“ -> see next slide

7 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch From single cryomodules to a CE stamped linac The cold part of the XFEL linac will be at the end one big CE stamped object The cold XFEL linac is also an assembly:  100 CE stamped cryomodules  ~ 100 sets of bellows for the cryomodule connections  String connection boxes and End/Feed caps with relief valves Why do we need to CE stamp the overall assembly, when each single component is produced following the PED and is CE stamped? To make it simple: if I buy 100 CE stamped pressure cookers and I use them at the same time on one gigantic stove in a small room  each cooker is safe but all together they are a big danger!

8 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch What are the different roles in the PED game? Manufacturer is responsible for the design  has to be certified as a producer of pressure vessels Producer (if not the manufacturer, i.e. not responsible for the design) has also to be certified (e.g. EN3834-2) External authority (notified body)  “only” verifies (if needed for the specific category)

9 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch A complicate example: the 3.9 GHz module Manufacturer is DESY, design is by INFN Milano Producer is Zanon (PED certified company) Delivered to DESY as part of the Injector linac Cavities verified by the external authority during the production, other components will be part of the bigger component

10 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch PART 2 Quality requirements versus Regulatory requirements

11 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Quality VS regulatory requirements The PED defines “minimum requirements for safe operation”; it doesn‘t guarantee that the object can be operated at the desired quality level for the whole operation time XFEL requires a 20 years operation without possibility of repairs on assembled modules  the manufacturer DESY impose more stringent requirements on the weld quality to guarantee the operation of the accelerator over 20 years with the required quality level The quality has also a direct impact on the inspection plan. What does this mean? If a component is built to the limit of the values allowed by the norm, the external authority can decide that in-service inspections (periodical reviews of the assembly) after the first commissioning are necessary  we absolutely want to avoid repeated inspections for the XFEL

12 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch An example: the Ti welds in the XFEL cryomodule PED relevant helium circuit welds performed during module assembly: the 2-phase line welds:  16 orbital welds on the Titanium 76.1 mm pipe (Ti76)  1 orbital weld on Stainless Steel 42.4 mm pipe (SS42) 9 orbital welds on the 8 mm warm up pipe capillaries 2 tack welds on the warm up pipe 2 lip welds on the quadrupole assembly

13 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Weld summary

14 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch 2-phase line welds: Ti76 and 8 mm capillaries

15 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch 2-phase line welds: quadrupole

16 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Non-Destructive Tests summary Non-Destructive Tests (NDT) on the PED relevant welds, as finally agreed with TÜV Nord in August 2013: For all the welds  100% Visual Test (VT)  100% Leak test (LT) For the orbital welds Ti76  100% Radiography Test (RT) For the orbital weld SS42  10% RT (after the first 5 tests, only 1/10 welds will be X-rayed)  90% liquid Penetrant Test (PT) For the lip welds and the tack welds  100% liquid Penetrant Test (PT)

17 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch What do we look for with NDTs? Typical problem for Ti welding pores are our main problem in the original material and in the welds done at Saclay Where do these pores come from? Titanium is a getter Cleanness Handling during welding Pre-existing pores in the original material Specifications of the 2-phase line Ti pipe for the XFEL allow „ASME like“ quality, with pores up to ~0.8 mm (agreement between DESY and TÜV Nord)

18 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Pore acceptance levels In the norm DIN EN ISO the acceptance levels for pores in the x-ray results are: Level 1:  diameter ≤ 0.4 mm (20% pipe thickness) Level 2:  diameter ≤ 0.6 mm (~30% pipe diameter) Level 3:  diameter ≤ 0.8 mm (45% pipe diameter) The PED requires pores ≤ 0.8 mm (level 3) REGULATION BUT DESY requires ≤ 0.4 mm (level 1) QUALITY

19 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Examples of pores on round welds

20 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Where did this Quality requirement brought us? Up to September 2013, no X-ray tests were done on cryomodules  Only on test pieces (always successful) First X-ray campaign on XM-1 on September 6th, only 3 welds acceptable at Level 1. Since the first welding campaign: DateLocationType of weldResults 05/ SACLAYXM-1: 1st welding campaign3 welds OK level 1, 13 NOT OK DESYTest welds on bellowsOK level DESY1st set of repaired bellows for XM-1OK level 1 with pores (parts rejected for assembly) DESY2nd set of repaired bellows for XM-1OK level 1 without pores SACLAYXM-1: 2nd welding campaign2 welds OK level 1, 2 welds NOT OK DESYTest welds and welding of spare bellowsOK level DESYTest welds bellows with EZ tanksOK level DESYTest welds bellows with 2 EZ tanks and an EZ cavityOK level DESYTest pieces with different pipesOK level SACLAYXM-1: 3rd welding campaign1 weld OK level 1, 3 welds OK level SACLAYTest welds with different Saclay welding machines2 welds OK level 1, 2 NOT OK DESYTest welds withe DESY and SACLAY weld machinesOK level 1 10/ SACLAYXM-1: 4th welding campaign7welds OK level 1, 7 OK level 2, 2 OK level 3

21 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Improvements at Saclay after the first welding campaign In the welding workshop  better overall preparation and cleanness  control of parasitic building ventilation (heating, doors) Welding tooling  metallic welding bladder exchanged with external support and rubber inner bladder He-Ar (50%-50%) gas  Careful check of gas quality  Bringing bottles to room temperature Ultrasonic cleaning of Ti bellows Welding of seamless tubes (on the cavity)

22 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Rework of the cavity 2-phase line Saclay

23 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Why do we want seamless pipes? Part of the longitudinal welds of the 2-phase line shows up in the radiography of the orbital welds The cryomodule is not acceptable, if a pore > 0.8 mm in the longitudinal weld shows up in the X-ray picture, even if the cavity is pressure tested, leak tested and already certified by TÜV If one or more pores are close to the pipe end during the orbital welding, they can be re-melted and included in the new weld, causing bigger pores on the orbital weld itself First welding campaigns and some additional X-ray campaigns performed on the longitudinal welds of cavities showed a low quality of the longitudinal welds of many pipes => The decision was taken to repair the 2-phase line on all the existing cavities, starting from XM5

24 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Example of a longitudinal weld with pores

25 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Images of the repair work Courtesy of D. Nölle

26 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Results of the latest welding campaigns

27 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Conclusions: our suggestions for the future accelerators Consider each pressurised component as a part of the whole system Definy as soon as possible in the design fase how you will deal with the safety and health regulations (do you need a CE stamp?) Clarify in advance the required documentation, including quality control documents, test reports, …, -> do not work „on the fly“; <- it‘s more efficient and cheaper If you need a CE stamp, work since the beginning in close contact with the certifying authority

28 Requirements Conformance for SRF cryomodules Workshop, ESS, Lund – 16/09/2014 k. Jensch Thank you for your attention!